Crash (computing) in the context of Exit (system call)

In the field of databases in computer science, a transaction log (also transaction journal, database log, binary log or audit trail) is a history of actions executed by a database management system used to guarantee ACID properties over crashes or hardware failures. Physically, a log is a file listing changes to the database, stored in a stable storage format.

If, after a start, the database is found in an inconsistent state or not been shut down properly, the database management system reviews the database logs for uncommitted transactions and rolls back the changes made by these transactions. Additionally, all transactions that are already committed but whose changes were not yet materialized in the database are re-applied. Both are done to ensure atomicity and durability of transactions.

A software bug is a design defect (bug) in computer software. A computer program with many or serious bugs may be described as buggy.

The effects of a software bug range from minor (such as a misspelled word in the user interface) to severe (such as frequent crashing).

In computing, a core dump, memory dump, crash dump, storage dump, system dump, or ABEND dump consists of the recorded state of the working memory of a computer program at a specific time, generally when the program has crashed or otherwise terminated abnormally. In practice, other key pieces of program state are usually dumped at the same time, including the processor registers, which may include the program counter and stack pointer, memory management information, and other processor and operating system flags and information. A snapshot dump (or snap dump) is a memory dump requested by the computer operator or by the running program, after which the program is able to continue. Core dumps are often used to assist in diagnosing and debugging errors in computer programs.

On many operating systems, a fatal exception in a program automatically triggers a core dump. By extension, the phrase "to dump core" has come to mean in many cases, any fatal error, regardless of whether a record of the program memory exists. The term "core dump", "memory dump", or just "dump" has also become jargon to indicate any output of a large amount of raw data for further examination or other purposes.

Uptime is a measure of system reliability, expressed as the period of time a machine, typically a computer, has been continuously working and available. Uptime is the opposite of downtime.

It is often used as a measure of computer operating system reliability or stability, in that this time represents the time a computer can be left unattended without crashing or needing to be rebooted for administrative or maintenance purposes.

In database systems, durability is the ACID property that guarantees that the effects of transactions that have been committed will survive permanently, even in cases of failures, including incidents and catastrophic events. For example, if a flight booking reports that a seat has successfully been booked, then the seat will remain booked even if the system crashes.

Formally, a database system ensures the durability property if it tolerates three types of failures: transaction, system, and media failures. In particular, a transaction fails if its execution is interrupted before all its operations have been processed by the system. These kinds of interruptions can be originated at the transaction level by data-entry errors, operator cancellation, timeout, or application-specific errors, like withdrawing money from a bank account with insufficient funds. At the system level, a failure occurs if the contents of the volatile storage are lost, due, for instance, to system crashes, like out-of-memory events. At the media level, where media means a stable storage that withstands system failures, failures happen when the stable storage, or part of it, is lost. These cases are typically represented by disk failures.

In engineering, a bug is a design defect in an engineered system—such as software, computer hardware, electronics, circuitry or machinery—that causes an undesired result. Defects outside the scope of design, such as a server crash due to a natural disaster, are not bugs, nor do bugs occur in natural systems such as the weather.

Bug is a non-technical term; more formal terms, besides defect, are error, flaw, and fault. Bugs may be persistent, sporadic, intermittent, or transient; in computing, crashes, freezes, and glitches are types of bugs.